The work described in this project is aimed at determining the structure, properties, and functions of intermediate filaments (IF) in mammalian cells. Many of the experiments take advantage of recently discovered properties of IF showing that they are dynamic cytoskeletal proteins. Dr. Goldman proposes to use specific peptides designed to disrupt IF assemblies in vivo using microinjection methods and to determine the physiological changes which accompany their disassembly. He also proposes to study the mechanisms by which phosphorylation modifies IF organization in cells using a variety of cellular and molecular approaches, including microscopic, biochemical, and immunological techniques. Another major goal is to determine the function of one of the major IF associated proteins, IFAP300. This protein appears to be involved in regulating the distribution and supramolecular organization of IF networks in cells via its crossbridging function. IFAP300 also appears to be involved in interactions with other cytoskeletal systems such as microtubules. In order to further understanding of the function of this protein, it is being cloned and sequenced using standard methods.